1. Field of the Invention
The present invention generally relates to a metallizing composition and particularly relates to a metallizing composition for metallizing a surface of alumina porcelain which is used as an insulating material of electronic parts.
2. Prior Art
Having little high frequency loss, alumina porcelain is generally used for electronic parts such as MIC substrates, microwave transmissible window materials, electron tubes, etc., after metallizing ink is printed on the surface of the alumina porcelain thereby metallizing the alumina porcelain to form desired print circuits or the like. It is a matter of course that the higher the content of alumina the more superior alumina character the alumina porcelain has. However, there have been developed no metallizing compositions improved in airtightness and contact, and therefore at present only a combination of a metallizing composition composed of tungsten of 100 parts by weight and alumina of 3 parts by weight and porcelain of 92% alumina to the utmost, is put into practice.
In recent years, however, low loss materials are required as the communication frequency is shifted into a high-frequency band and as the frequency of magnetrons is made high. Accordingly, there have been strong demands on practical use of alumina porcelain having purity higher than 96% by weight which is conventional to electronic devices.